Answer:
D
Explanation:
For it to be a function, every x value must have 1 unique y value ONLY.
In option A, you can see that the x value of 1 has 2 y values, 1 & 5. So it's not a function.
In option B, you can see that the x value of 0 has 2 y values, 0 & -4. Moreover, the x value of 4 also has 2 y values, 2 & -2. So it's not a function.
In option C, you can see that the x value of -2 has 2 y values, 4 & -4. This is not a function as well.
In option D, each x value has a unique y value that are different. So this is a function.
Answer is option D.